Newborn babies have not been exposed to an increased health risk by their mothers being vaccinated against Covid-19, a study has found.
On the contrary, the research indicated the chances of babies of inoculated mothers developing serious neonatal complications were reduced.
The largest study focusing on the safety of newborn babies whose mothers were vaccinated during pregnancy found the mortality rate was reduced.
Lead author Mikael Norman, professor of paediatrics and neonatology at the Karolinska Institutet in Solna, Sweden, told The National his team was surprised at the results and remained puzzled over the reason behind the higher rates of protection afforded to babies of immunised mothers.
"The lower risk for neonatal death and neonatal brain lesions in babies to mothers who were vaccinated in pregnancy surprised us," he said.
"We did not expect the lower risk for neonatal death to be so robust, even after taking several background factors into account, such as maternal age, BMI, education, country of birth, smoking status, season of conception, parity, multiple births and gestational age.
"Analyses restricted to women without Covid-19 in pregnancy, or to infants born at term, infants without birth defects and singleton births did not alter the findings.
“We made several attempts to explain this finding. A direct vaccine effect is unlikely. Previous studies have shown that the vaccine does not cross the placenta and that it cannot be found in umbilical cord blood.”
The study, published in the medical journal JAMA, was a collaboration between Swedish and Norwegian scientists.
Researchers observed 200,000 newborns in both countries and conducted seven subgroup analyses of women and their babies.
Prof Norman said it was of vital importance to understand the root causes of the findings.
“No matter how we look at it, the finding remains and therefore we cannot say what the lower risk of death among infants of vaccinated women relates to,” he said.
"So far, we haven´t decided how to proceed. While we have large numbers of women and robust data, we are limited by the variables available in our national registers."
The researchers used national registers in Norway and Sweden and included 98 per cent of all newborn babies of women who became pregnant after Covid-19 vaccines became available.
All births from gestational week 22 onwards were included.
The first baby analysed was born in June 2021 and the last in January 2023. All babies were followed up for at least one month or for as long as they were admitted to a neonatal unit.
The study included 196,470 newborns of whom 48 per cent of their mothers had been vaccinated with one or more doses of an mRNA vaccine against Covid-19.
Almost 80 per cent had received the Pfizer/BioNTech shot and a little more than 20 per cent had had the Moderna vaccine.
In addition to a lower number of infant deaths, the researchers also found a significantly reduced risk of two other serious complications in infants born to mothers who had been vaccinated.
In total, 15 neonatal complications and conditions were studied.
“We saw lower rates of cerebral haemorrhages and hypoxia-ischemic conditions of the brain in the newborns of vaccinated than in babies of unvaccinated in pregnancy, while the incidence of other bleeding, blood clots or inflammation in various organ systems did not differ between the groups,” Prof Norman said.
He said the findings were of “great importance” for health professionals offering counselling, authorities issuing recommendations and for anyone who will become pregnant in the future.
“Covid-19 is still present in society and is probably something we will have to deal with for a long time,” he said.
“It is therefore very important for the 100,000 women who become pregnant every year in Sweden, and the 130 million in the world, to know that vaccination with mRNA-vaccines against Covid-19 is safe for their babies. We found no increased risks – if anything, infants to vaccinated women had lower risks for some severe outcomes.”
He said he hoped the research would encourage more people to take up the vaccine.
"Our findings are good news for pregnant women who want to protect themselves and their babies in the future," Prof Norman said.
